https://github.com/sleavely/json-changes

Compare 👥 and extract 🔬 differences between JSON values
https://github.com/sleavely/json-changes

diff javascript nodejs

Last synced: 1 day ago
JSON representation

Compare 👥 and extract 🔬 differences between JSON values

• Host: GitHub
• URL: https://github.com/sleavely/json-changes
• Owner: Sleavely
• License: mit
• Created: 2022-04-06T10:51:28.000Z (over 2 years ago)
• Default Branch: main
• Last Pushed: 2022-04-06T15:18:42.000Z (over 2 years ago)
• Last Synced: 2024-10-30T14:33:25.849Z (15 days ago)
• Topics: diff, javascript, nodejs
• Language: JavaScript
• Homepage:
• Size: 49.8 KB
• Stars: 3
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

README

        
# json-changes

Easily compare changes in JSON-like values. This can be especially useful when you want to compare an incoming payload with a counterpart stored in a database.

[ ![npm version](https://img.shields.io/npm/v/json-changes.svg?style=flat) ](https://npmjs.org/package/json-changes "View package")

[ ![CI status](https://github.com/Sleavely/json-changes/actions/workflows/node.js.yml/badge.svg) ](https://github.com/Sleavely/json-changes/actions/workflows/node.js.yml "View workflow")

## Installation

```sh

npm i json-changes

```

## Usage

First, let's define our flags in a file we'll call `permissions.js`:

```js

const diff = require('json-changes')

const before = { hello: 'world', foo: 'bar', thisPropertyNoLongerExists: true }

const after = { hello: 'world', foo: 'not bar' }

const comparison = diff(before, after)

// returns:

{

  before: {

    foo: 'bar',

    thisPropertyNoLongerExists: true

  },

  after: {

    // Only properties that changed are included

    foo: 'not bar',

    // Properties that have been removed have an undefined value;

    thisPropertyNoLongerExists: undefined

  }

}

```

It works recursively in nested objects as well:

```js

const before = { nestedObj: {} }

const after = { nestedObj: { evenMoreNestedObject: { thisPropIsNew: 'Hello, new property!' } } }

const comparison = diff(before, after)

// returns:

{

  before: {

    nestedObj: { evenMoreNestedObject: undefined }

  },

  after: {

    nestedObj: {

      evenMoreNestedObject: {

        thisPropIsNew: 'Hello, new property!'

      }

    }

  }

}

```

### undefined values

Encountering an `undefined` value in the comparison means that the property either did not exist in `before` or was removed in `after`.

_json-changes_ is primarily meant to be used to compare JSON, so `undefined` is assumed to never be used in the payloads being compared.